package com.yiruantong.common.ratelimiter.aspectj;

import cn.hutool.core.util.ArrayUtil;
import com.yiruantong.common.core.constant.GlobalConstants;
import com.yiruantong.common.core.exception.ServiceException;
import com.yiruantong.common.core.utils.MessageUtils;
import com.yiruantong.common.core.utils.ServletUtils;
import com.yiruantong.common.core.utils.StringUtils;
import com.yiruantong.common.ratelimiter.annotation.RateLimiter;
import com.yiruantong.common.ratelimiter.enums.LimitType;
import com.yiruantong.common.redis.utils.RedisUtils;
import lombok.extern.slf4j.Slf4j;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.reflect.MethodSignature;
import org.redisson.api.RateType;
import org.springframework.core.DefaultParameterNameDiscoverer;
import org.springframework.core.ParameterNameDiscoverer;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.Expression;
import org.springframework.expression.ExpressionParser;
import org.springframework.expression.ParserContext;
import org.springframework.expression.common.TemplateParserContext;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.expression.spel.support.StandardEvaluationContext;

import java.lang.reflect.Method;

/**
 * 限流处理
 *
 * @author YiRuanTong
 */
@Slf4j
@Aspect
public class RateLimiterAspect {

  /**
   * 定义spel表达式解析器
   */
  private final ExpressionParser parser = new SpelExpressionParser();
  /**
   * 定义spel解析模版
   */
  private final ParserContext parserContext = new TemplateParserContext();
  /**
   * 定义spel上下文对象进行解析
   */
  private final EvaluationContext context = new StandardEvaluationContext();
  /**
   * 方法参数解析器
   */
  private final ParameterNameDiscoverer pnd = new DefaultParameterNameDiscoverer();

  @Before("@annotation(rateLimiter)")
  public void doBefore(JoinPoint point, RateLimiter rateLimiter) throws Throwable {
    int time = rateLimiter.time();
    int count = rateLimiter.count();
    String combineKey = getCombineKey(rateLimiter, point);
    try {
      RateType rateType = RateType.OVERALL;
      if (rateLimiter.limitType() == LimitType.CLUSTER) {
        rateType = RateType.PER_CLIENT;
      }
      long number = RedisUtils.rateLimiter(combineKey, rateType, count, time);
      if (number == -1) {
        String message = rateLimiter.message();
        if (StringUtils.startsWith(message, "{") && StringUtils.endsWith(message, "}")) {
          message = MessageUtils.message(StringUtils.substring(message, 1, message.length() - 1));
        }
        throw new ServiceException(message);
      }
      log.info("限制令牌 => {}, 剩余令牌 => {}, 缓存key => '{}'", count, number, combineKey);
    } catch (Exception e) {
      if (e instanceof ServiceException) {
        throw e;
      } else {
        throw new RuntimeException("服务器限流异常，请稍候再试");
      }
    }
  }

  public String getCombineKey(RateLimiter rateLimiter, JoinPoint point) {
    String key = rateLimiter.key();
    // 获取方法(通过方法签名来获取)
    MethodSignature signature = (MethodSignature) point.getSignature();
    Method method = signature.getMethod();
    Class<?> targetClass = method.getDeclaringClass();
    // 判断是否是spel格式
    if (StringUtils.containsAny(key, "#")) {
      // 获取参数值
      Object[] args = point.getArgs();
      // 获取方法上参数的名称
      String[] parameterNames = pnd.getParameterNames(method);
      if (ArrayUtil.isEmpty(parameterNames)) {
        throw new ServiceException("限流key解析异常!请联系管理员!");
      }
      for (int i = 0; i < parameterNames.length; i++) {
        context.setVariable(parameterNames[i], args[i]);
      }
      // 解析返回给key
      try {
        Expression expression;
        if (StringUtils.startsWith(key, parserContext.getExpressionPrefix())
          && StringUtils.endsWith(key, parserContext.getExpressionSuffix())) {
          expression = parser.parseExpression(key, parserContext);
        } else {
          expression = parser.parseExpression(key);
        }
        key = expression.getValue(context, String.class) + ":";
      } catch (Exception e) {
        throw new ServiceException("限流key解析异常!请联系管理员!");
      }
    }
    StringBuilder stringBuffer = new StringBuilder(GlobalConstants.RATE_LIMIT_KEY);
    stringBuffer.append(ServletUtils.getRequest().getRequestURI()).append(":");
    if (rateLimiter.limitType() == LimitType.IP) {
      // 获取请求ip
      stringBuffer.append(ServletUtils.getClientIP()).append(":");
    } else if (rateLimiter.limitType() == LimitType.CLUSTER) {
      // 获取客户端实例id
      stringBuffer.append(RedisUtils.getClient().getId()).append(":");
    }
    return stringBuffer.append(key).toString();
  }
}
